Foveal vision corresponds to viewing conditions for which the image of an object looked at is formed by the eye in the central zone of the retina, called the foveal zone.
Peripheral vision corresponds to the perception of elements of a scene that are offset laterally relative to the object looked at, the images of said elements being formed on the peripheral portion of the retina, away from the foveal zone.
Firstly, the ophthalmic correction with which an ametropic subject is provided is adapted for his foveal vision. However, as is known, the correction has to be reduced for the peripheral vision relative to the correction that is determined for the foveal vision. In particular, studies carried out on monkeys have shown that strong defocusing of the light behind the retina, which occurs away from the foveal zone, may cause the eye to extend and therefore may cause a myopia defect to increase. Spectacle eyeglasses have therefore been proposed, for example such as those described in the document WO 2007/041796, which comprise a central zone dedicated to the correction of the foveal vision and a peripheral zone dedicated to the peripheral vision. Thus, two separate ophthalmic correction values may be obtained, which are adapted for the foveal vision and for the peripheral vision respectively. However, such lenses do not provide an appropriate correction when the wearer looks at an object by rotating his eyes. This is because he then uses his foveal vision through a lateral zone of the lens which was adapted for his peripheral vision.
Document EP 0 367 878 describes an eyeglass having concentric zones that has several focal lengths at any point on its surface. Such an eyeglass may provide two ophthalmic correction values simultaneously, for example one for the foveal vision and the other for the peripheral vision, irrespective of the direction of viewing through the eyeglass. However, because some of the optical power is provided by a light diffraction effect, the eyeglass exhibits strong chromatism. The effective optical power of the eyeglass cannot therefore be precisely matched for all colours relative to the sphere error determined for an ametropic person.